1. Field of the Invention
The present invention relates to an image display apparatus such as a television picture signal, and more specifically, to an image display apparatus provided with a matrix panel.
2. Description of the Related Art
In the related art, as an image display apparatus of this type, there is a known configuration provided with a multi-electron-source in which N×M cold cathode elements (image display elements) are arranged in two-dimensional matrix of N-rows and M-columns and are interconnected in a simple matrix by M row wirings (scanning wiring) provided in the row direction and N column wirings (modulation wiring) provided in the column direction. In this specification, this configuration is referred to as “matrix panel in which the cold cathode elements are interconnected into a simple matrix”. However, it is not limited to the cold cathode elements, and a configuration in which image display elements are interconnected into a matrix including a plurality of row wirings and a plurality of column wirings is also referred to as “matrix panel”.
In a typical driving method, a number of image display elements (for example cold cathode elements) interconnected into a matrix, a group of elements constituting a row of the matrix (the group of element constituting a row is connected to one row wiring) is driven simultaneously.
In other words, a predetermined selected voltage is applied to one row wiring, and a predetermined modulating voltage is applied only to column wiring which is connected to cold electrode elements to be driven out of N cold electrode elements connected to the specific row wiring, so that a plurality of elements constituting one row are driven simultaneously by the difference in potential between the row wiring potential and the column wiring potential. Then all the rows are scanned by switching the selected row in sequence to form a two-dimensional image utilizing an after-image phenomenon.
There are methods of driving a matrix panel disclosed in JP-A-2000-29425, JP-A-2002-311885, and WO/1267319 of the present applicant. There are also methods of driving a matrix panel disclosed in JP-A-2002-232905 and in JP-A-1-209493.
In JP-A-2000-29425, a modulating voltage is applied by a modulation circuit of pulse width modulating system to control the cycle of a reference clock (PCLK) for a pulse width modulation. This method is adapted to realize a gradation characteristic as that of the CRT when a signal which was gamma-corrected in advance for being displayed in CRT, such as a TV signal, is supplied.
In the method disclosed in JP-A-2002-311885, a modulating voltage is applied by a modulation circuit which employs such modulation system that when a predetermined pulse width is achieved as a result of performing the pulse width modulation, the pulse width modulation is performed with the next higher potential. This method is adapted to set a plurality of potentials (V0–Vm) to realize a brightness characteristic as that of the CRT when a signal which is gamma corrected in advance for being displayed in CRT, such as a TV-signal, is supplied. This publication also discloses a technology for adapting the gradation characteristic, which is realized by the preset potential (V0–Vm) and is different from the CRT, to the gradation characteristic of the CRT by a brightness data converter.
With these methods, when a signal which is gamma corrected in advance for being displayed in CRT, such as a TV signal, is supplied, it can be displayed preferably in a matrix panel.
JP-A-2002-232905 discloses a method of implementing reproduction of colors of CRT in the LCD.
JP-A-1-209493 discloses a configuration in which the relation between the display level and the brightness which is sensed by human eyes based on light emission from a light-emitting point of a self-luminous display device is controlled to be a substantially linear.
WO/1267319 discloses a configuration in which a modulation is performed in combination of a crest value modulation and a pulse width modulation, and also a configuration in which the rising portion and falling portion of the waveform of a signal are formed into a step-form.